The present invention relates to a fuel injection system as claimed in claim 1. p On known injection systems of this type, as per patent applications DE-OS 32 27 742 and EP-OS 0 149 598, the pressure accumulator is permanently connected to a duct on each injector via an annular compartment and throttle valve. Each injector presents an injection electrovalve for connecting the said duct to a fuel feedback pipe, thus releasing a pin on the injector closing the injection opening, and enabling fuel supply from a pressure compartment directly upstream from the injection opening. Fuel is supplied to the accumulator at a given pressure by means of a high-pressure hydraulic pump powered by the drive shaft via a gear, and the size of which depends on minimum required pressure at low engine speed, maximum fuel injection, and minimum pressure regulating speed. The disadvantage of such a system from the manufacturing standpoint is that pump design must conform with the requirements of different power engines, if optimum engine performance in terms of consumption and output is to be assured. This therefore amounts to manufacturing and storing a different pump for each type of engine, which inevitably results in increased manufacturing costs.
A further drawback of known systems of the aforementioned type is that, being constant and designed to cater to maximum requirements, fuel supply by the high-pressure pump is invariably in excess of actual consumption, so that a large percentage of the fuel supplied by the pump must be fed back to the tank via a pressure regulator, the energy loss of which increases overall consumption or at least affects output of the engine.
Yet a further drawback of known systems is that overheating of the fuel at the bottom of the tank often entails assembling an intercooler, which, in addition to further increasing manufacturing cost, may also increase fuel consumption.